Pressure sensor for detecting the pressure in the combustion chamber of internal-combustion engines

Abstract

In a pressure sensor, the force is introduced onto a piezoresistive measuring element via a diaphragm and a punch. Since no exact mechanical adjustment between the diaphragm and the measuring element is necessary, various relatively inexpensive forms of diaphragm with different measuring sensitivity can be used. The punch and the piezoresistive measuring element can be pushed through an opening in the housing and pressed onto the diaphragm so as to provide an interlocking frictional connection between the punch and the measuring element.

We claim: 
     
       1. A process for producing a pressure sensor for detecting pressure in a combustion chamber of internal combustion engines and having a diaphragm, a measuring element and a punch, the process comprising the steps of fastening a diaphragm on a housing in a region of a first opening of the housing; and introducing a punch and a piezo-resistive measuring element through a second opening of the housing into the housing and pressing the punch onto the diaphragm in such a way that a form fit is produced between the punch and the measuring element. 
     
     
       2. A process for producing a pressure sensor for detecting pressure in a combustion chamber of internal combustion engines and having a diaphragm, a measuring element and a punch, the process comprising the steps of fastening a diaphragm on a housing in a region of a first opening of the housing; introducing a punch and a piezo-resistive measuring element through a second opening of the housing into the housing and pressing onto the diaphragm in such a way that a form fit is produced between the punch and the measuring element; and pressing a counterbearing for the punch so far into the housing that an impression of the punch is produced on one of the piezo-resistive measuring elements and a glass layer surrounding the piezo-resistive measuring element. 
     
     
       3. A process as defined in claim 2, and further comprising the step of placing the diaphragm onto a shank of the housing, which shank has the first opening, so that no mechanical adjustment is needed between the piezo-resistive measuring element and the diaphragm. 
     
     
       4. A pressure sensor for detecting pressure in a combustion chamber of internal combustion engines, comprising a housing; a diaphragm and a measuring element provided in said housing; a punch arranged between said diaphragm and said measuring element in said housing and introducing a pressure onto said measuring element, said measuring element being formed as a piezo-resistive element, said diaphragm being fastened to said housing so that no mechanical adjustment is needed between the piezo-resistive measuring element and the diaphragm, said housing having a shank, said diaphragm being fastened on said shank of the housing. 
     
     
       5. A pressure sensor as defined in claim 4, wherein said shank of said housing has a recess, said diaphragm being arranged in said recess of said shank of said housing. 
     
     
       6. A pressure sensor as defined in claim 5, wherein said shank of said housing has an inner wall provided with an annular groove. 
     
     
       7. A pressure sensor for detecting pressure in a combustion chamber of internal combustion engines, comprising a housing; a diaphragm and a measuring element provided in said housing; a punch arranged between said diaphragm and said measuring element in said housing and introducing a pressure onto said measuring element, said measuring element being formed as a piezo-resistive element, said diaphragm being fastened to said housing so that no mechanical adjustment is needed between the piezo-resistive measuring element and the diaphragm, said diaphragm being formed as a plate. 
     
     
       8. A pressure sensor for detecting pressure in a combustion chamber of internal combustion engines, comprising a housing; a diaphragm and a measuring element provided in said housing; a punch arranged between said diaphragm and said measuring element in said housing and introducing a pressure onto said measuring element, said measuring element being formed as a piezo-resistive element, said diaphragm being fastened to said housing so that no mechanical adjustment is needed between the piezo-resistive measuring element and the diaphragm, said diaphragm having a side facing said punch and is provided with at least one annular groove in said side. 
     
     
       9. A pressure sensor for detecting pressure in a combustion chamber of internal combustion engines, comprising a housing; a diaphragm and a measuring element provided in said housing; a punch arranged between said diaphragm and said measuring element in said housing and introducing a pressure onto said measuring element, said measuring element being formed as a piezo-resistive element, said diaphragm being fastened to said housing so that no mechanical adjustment is needed between the piezo-resistive measuring element and the diaphragm, said diaphragm having a bending region formed by a spiral depression. 
     
     
       10. A pressure sensor for detecting pressure in a combustion chamber of internal combustion engines, comprising a housing; a diaphragm and a measuring element provided in said housing; a punch arranged between said diaphragm and said measuring element in said housing and introducing a pressure onto said measuring element, said measuring element being formed as a piezo-resistive element, said diaphragm being fastened to said housing so that no mechanical adjustment is needed between the piezo-resistive measuring element and the diaphragm, said diaphragm having a bending region formed as a conically running section. 
     
     
       11. A pressure sensor for detecting pressure in a combustion chamber of internal combustion engines, comprising a housing; a diaphragm and a measuring element provided in said housing; a punch arranged between said diaphragm and said measuring element in said housing and introducing a pressure onto said measuring element, said measuring element being formed as a piezo-resistive element, said diaphragm being fastened to said housing so that no mechanical adjustment is needed between the piezo-resistive measuring element and the diaphragm, said diaphragm having a continuation provided in a region of said punch. 
     
     
       12. A pressure sensor for detecting pressure in a combustion chamber of internal combustion engines, comprising a housing; a diaphragm and a measuring element provided in said housing; a punch arranged between said diaphragm and said measuring element in said housing and introducing a pressure onto said measuring element, said measuring element being formed as a piezo-resistive element, said diaphragm being fastened to said housing so that no mechanical adjustment is needed between the piezo-resistive measuring element and the diaphragm, said diaphragm having a bending region formed by a radially encircling wave. 
     
     
       13. A pressure sensor for detecting pressure in a combustion chamber of internal combustion engines, comprising a housing; a diaphragm and a measuring element provided in said housing; a punch arranged between said diaphragm and said measuring element in said housing and introducing a pressure onto said measuring element, said measuring element being formed as a piezo-resistive element, said diaphragm being fastened to said housing so that no mechanical adjustment is needed between the piezo-resistive measuring element and the diaphragm, said punch having an end, said diaphragm having a substantially S-shaped region in an area of said end of said punch as seen in a cross-section.